Multi-storey buildings may be constructed by several techniques using several different types of material eg. structural steel, reinforced concrete either in situ or precast or any combination thereof. The builder may be required to construct or erect the structure including beams, columns, slabs and walls etc. as a whole or one level at a time. If the building is to be constructed one level at a time, each level may be constructed at its final floor to floor distance using conventional or proprietary formwork methods or for example with a structural steel frame building, each structural element would be lifted into place by a crane.
The use of a crane to lift main elements of the structure into place on a building may cause these operations lie directly on the critical path of the building programme. In other words, the speed of construction may be limited by the performance of the lifting crane.
Slabs, walls etc may be formed in-situ but the use of formwork to support in-situ concrete slabs requires substantial labour and materials. The handling and movement of formwork materials from floor to floor is also labour intensive and occupies excessive time on site. If a crane is used to lift or move these formwork materials, the time available for the crane to lift the other structural elements of the building is reduced.
Wall form building systems, such as slip form, also require their own lifting apparatus.
Another method of multi-storey building construction is known as "lift-slab". This method uses a floor slab surface as a soffitt to form another slab. The slab is formed by pouring directly on top of the lower slab. Proprietary material may be used to prevent the two slabs sticking together. Any number of floors and an equal number of columns in height may be cast one on top of each other. Using a lifting apparatus positioned and anchored on top of each column, each slab is then lifted into place starting with the last poured slab. Each slab is connected to the column of the building prior to the slab below being lifted.
Such a method requires the slabs to be formed with openings through which the column may slide-to allow movement of a slab to its final desired position. It is necessary, however, in the "lift-slab" method for each concrete slab to be fully cured prior to lifting. Clearly substantial time may be wasted waiting for curing of each slab prior to lifting.
These prior art methods all require substantial lifting apparatus such as cranes etc. and structural formwork to lift and position each slab, as well as continued incremental movement of these elements to each new floor level. Considerable time and expense is incurred in dismantling each set of formwork from one floor and moving it to the next floor for re-assembly.
In an effort to ameliorate the disadvantages of the prior art, therefore, it is proposed to provide a building construction method and apparatus which offers a choice over the prior art and which, at least in the preferred embodiments, is less expensive and time consuming as compared to the above mentioned prior art methods.